One of the things I like about my QS8s is that they are up and out of the way. A floor-standing surround gets in the way and ends up being in a listener's face. The diffuse sound also works very well in my room now and gives a very wide sound stage in DPLII.
I wonder however how much better the sound might be with the QS10HPs. I also wonder if the QSs might sound better in a larger room like mine if they had a less diffuse radiation pattern. For example, if the top and bottom firing drivers were angled 30 or maybe 45 degrees into the room.